/*
    This file is part of the substandard lisp implementation of Standard Lisp
    Copyright (C) 2011 Nicky Nickell

    substandard lisp is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

function std_reverse(a, env) {
  var u = a[0];

  var elements = [];
  for (var p = u; p != NIL; p = p.cdr) {
    elements.push(p.car);
  }

  var head = new lisp_pair(elements[elements.length - 1], NIL);
  var ptr = head;

  for (var i = elements.length - 2; i >= 0; i--) {
    ptr.cdr = new lisp_pair(elements[i], NIL);
    ptr = ptr.cdr;
  }

  return head;
}

/*---
name: reverse
arity: 1
rest: false
ftype: FTYPE_EXPR

argument-types:
  - TYPE_PAIR

doc: |
  explaining what reverse is / how it is used!

tests: |
  (reverse '(1 2 3 4)) -> (4 3 2 1)
  (setq a '(1 2 3 4 5))
  (reverse a) -> (5 4 3 2 1)
  a -> (1 2 3 4 5)
  (reverse '(a b c d 1 2.1)) -> (2.1 1 d c b a)
...*/
